Multiple zone injection apparatus for well bores



May 16, 1967 D. v. cHENowETH 3,319,717

MULTIPLE ZONE INJECTION APPARATUS FOR WELL BORES 2 Sheets-Sheet 1 Hy JMM/ rrofeA/Ev.

Filed Oct. 4, 1965 May 16, 1967 D. v. CHENQWETH MULTIPLE ZONE INJECTION APPARATUS FOR WELL BORES Filed Oct. 4. 1965 2 Sheets-Sheet 2 i. W ME N f .mm .w u CM V w@ W B 3,319,717 MULTEPLE ZNE INJECTON APPARATUS FOR WELL EURES David V. Clienoweth, Houston, Tex., assignor to Baker @il Tools, Inc., City of Commerce, Calif., a corporation of California Filed st. 4, 1965, Ser. No. 492,750 17 Claims. (Cl. 16d-115) ABSTRACT 0F THE DESCLOSURE Apparatus for injecting fluids from the top of a well bore through a single string of tubing individually into a plurality of formation zones, an individual ow regulator in the tubing at each Zone embodying an orifice through which the fluid is forced, the pressure drop through each orice being held substantially constant by a throttle valve device to insure substantially constant rate of flow through the orice regardless of variations in upstream or downstream pressures. In addition, each regulator inlet from the tubing is substantially below the regulator outlet to cause solids in the tubing iluid stream to drop to the lbottom of the tubing and prevent their interfering with operation of each regulator.

The present invention relates to well bore apparatus, and more aprticularly to apparatus for injecting fluids into a well bore.

There are economic advantages to injecting iluid into a plurality of well bore formation zones through use of a single string of tubing, since it eliminates the need for installing multiple tubing strings in the well bore and the provision of associated relatively costly multiple string packers and related equipment. In the present case, a single string of tubing is used for injecting uids into a plurality of zones in a well bore, the injection of uid into each zone occurring at a predetermined and constant volumetric rate through use of an individual ow regulator, the rate of injection remaining constant despite variations in the iluid pressure in the tubing string or in the formation zone, or both. The ow regulator is so disposed in the tubing string as to prevent solids entrained in the duid stream from passing through the regulator and possibly plug-ging it or interfering with its proper operation. The flow regulators may be of the retrievable type, in that they may be moved through the tubing string and latched in desired position therein, and, if desired, withdrawn through the tubing string to the top of the well bore. Since only a single tubing string is used in t-he well bore, the packers associated therewith in isolating the formation zones from one another can be relatively simple, being either of the permanent or retrievable type.

This invention possesses many other advantages, and has other purposes which may be made more clearly apparent from a consideration of a form in which it may be embodied. This form is shown in the drawings accompanying and forming part of the present specication. It will now be described in detail, for the purpose of illustrating the general principles of the invention; but it is to be understood that such detailed description is not to be taken in a limiting sense, since the scope of the invention is best defined by the appended claims.

Referring to the drawings:

FIGURE l is a diagrammatic view of a cased well bore, with apparatus embodying the invention therein for injecting iiuids into longitudinally spaced formation zones;

FIG, 2 is a longitudinal section through one form of flow regulator for injecting fluid into the well bore;

I United States Patent O FIGS. 3a and 3b together constitute a longitudinal section through a flo-w regulator installed in the tubing string, FIG. 3b being a lower continuation of FIG. 3a.

As disclosed in the drawings, it is desired to inject fluid at a predetermined rate into each of a plurality of zones A, B, C, D in a well bore E, in which a string of casing F has been installed, the casing string having longitudinally spaced perforations 10, 11, 12 or 13 therethrough at each formation Zone. The Zones are separated from one another by well packers 14, 15, 16 set in leakproof relation in the casing and also sealed with respect to a tubing string H connected to each of the packers, and which extends through a well head .I at the top of the well bo-re. These well packers may be of the permanent or retrievable type, as desired. As disclosed, a ilow regulator 17 is incorporated in the tubing string below the lowermost packer 14 and between the packers 14, 15 and 15, 16 for the purpose of controlling the rate at which iiuip pumped down through the tubing string H can be injected through the perforations into each formation zone A, B, C. Each flow regulator is of the type that will cause the huid to be injected at a constant volumetric rate into the formation zone.

The flow regulators connected to the tubing string are disclosed in FIG. l for purposes of convenience of illustration as bein-g of larger diameter than the inside diameter of the diagrammatically illustrated packers 14, 15, 16 which are in sealed relation with the tubing string. It is to be understood, however, that the flow regulator portions of the tubing string may have a diameter no greater than the passage through the packers, assuming the latter to be of the permanent type, so that the tubing string can be withdrawn from the well bore, if desired. In the event that the packers are of the retrievable type, then the flow regulators can be of a larger diameter than the diameter of the packer passages, since they can be withrawn from the well bore simultaneously with the release and elevation of the well packers from and within the well casing.

As illustrated in FIG. l, the uppermost zone D, if desired, can be separated injected with fluid pumped through tubing M that has a surface ilow regulator 18 therein, the iluid from the surface ilow regulator discharging into the annulus 19 above the uppermost well packer 16 and between the tubing string H and casing F.

The flow regulators 17 below the lowermost packer and between the packers can be of essentially the same type, such as of the retrievable type illustrated in FIGS. 3a and 3b. They could also be of a non-retrievable type, if desired. As shown therein, each ilow regulator 17 includes an outer housing structure Ztl consisting of an upper sub 21 threadedly secured to a section of the tubing string H thereabove, and which is also threadedly secured to the main outer housing or body section 22, the lower end of which is threadedly attached to a lower housing or body sub 23, which is, in turn, threadedly secured to a lower section of the tubing string H. Disposed within the outer housing 20 is an inner housing 24, which comprises a central cylindrical or sleeve-like portion 25 having an upper flange 26 adapted to bear against the lower end of the upper sub 21 and a lower flange 27 adapted to bear against the upper end of the lower housing sub 23. These flanges have longitudinal passages 28, 29 therethrough to permit fluid to flow through the upper -housing sub 21 and the passages 28, between the annular space 30 between the inner housing 24 and outer housing section 22, and through the lower ange passages 29 into the lower sub 23. Spaced outwardly from the inner housing portion 25 is a sleeve 31 extending across circumferential spaced ports 32 in the outer housing member 22, and which has seal rings 33 thereon on opposite sides of the ports sealingly engaging the inner wall of the housing section 22. A boss 34 interconnects the inner housing portion 25 and the outer sleeve 31 which has a port 35 extending therethrough opening into a peripheral groove 36 in the outer housing which communicates with the outer housing ports 32. A check valve or back pressure valve member 37 is located in the boss and is adapted to move laterally inwardly into engagement with a valve seat 38 surrounding the boss passage to prevent inward flow of fluid through its port 35. Outward movement of the ball valve element is limited by its engagement with the outer housing member 22. The outer ports 32 are formed as slots having a width less than the diameter of the ball valve member 37, so that the latter will be retained within the passage extending through the boss.

The main portion of the flow regulator device is located within the inner housing member 24 and is releasably retained therewithin. Such device includes a central mandrel 40 composed of several sections. An upper tubular lock section 41 is provided having a plurality of circumferentially spaced slots 42 therein in which locking dogs or latch members 43 are mounted on pivot pins 44 extending across the slots and suitably secured to the mandrel section. The lower lock portions 45 of these lock dogs 43 are adapted to be received within an internal circumferential groove 46 in the upper portion of the inner housing member 24, being urged outwardly into such groove by helical compression springs 47 bearing against the inner base of each slot and also against the dog portions 45. When the lock dogs have been expanded outwardly into the groove 46, which will prevent downward movement of the lock mandrel 41 within the housing structure, upper nose portions 48 of the lock dogs or latches project partially into the central passage 49 through the mandrel section. Through use of a suitable retrieving tool (not shown) of a known type, a probe of the latter will extend into the mandrel passage 49, enJ gaging the noses 48 of the lock dogs to shift their upper portions outwardly and retract their lower portions 45 inwardly from the housing groove 46, thereby releasing the mandrel from the housing. At the same time, as is known in the art, an overshot, or the like, on the retrieving tool moves over the upper head portion 50 of the lock 'section for the purpose of elevating the mandrel 40 through the tubing string H.

The lower end of the lock section 41 is threadedly secured to a flow section 51 of the mandrel that has a solid upper head portion 52 and a central passage 53, the upper end of which opens through a side port 54 into a peripheral groove 55. This groove is disposed opposite the passage 35 through the inner housing member 24 and its boss 34 when the lock dogs 43 are expanded outwardly into the groove 46. The flow mandrel section 51 carries a suitable seal ring 56 for sealing against the wall of the inner housing Iportion 25 above the port 35, and also a lower seal ring 57 for sealing against the wall of the inner housing section below the port, as illustrated in FIGS. 3a and 3b. The upper seal 56 is held on the flow mandrel section 51 by the lock mandrel section 41, and the lower seal 57 is held on the flow mandrel section by a regulator housing section 58 of the mandrel structure 40 that will extend downwardly into the lower housing sub 23 in spaced relation to the inner wall 59 of the latter.

The regulator housing 58 has a plurality of circumferentially spaced side ports 60 for the flow of fluid from the lower sub 23 into an annular space 61 between the lower inner wall 62 of the housing and a cylinder sleeve 63 within the housing, the upper end of which is disposed within a smaller internal diameter portion 64 of the housing 58 and abuts the lower end of the flow mandrel section 51. The lower end of the cylinder sleeve 63 engages a flange 65 of a lower plug 66 piloted within the lower endof the cylinder sleeve 63 and having a reduced diameter stem portion 67 extending upwardly within the latter and in spaced relation therewith to define an annular cylinder space 68 therewithin in which a piston or valve sleeve 69 is slidable, this piston or valve sleeve also being slidable along the inner wall of the cylinder sleeve 63. Leakage of fluid in an upward direction between the cylinder sleeve 63 and housing 58 is prevented by a suitable seal ring 70 on the cylinder sleeve engaging the inner wall 64 of the housing; whereas, leakage of fluid between the plug 66 and the cylinder 63 is prevented by a suitable side seal ring 71 on the plug engaging the inner wall of the cylinder sleeve.

Fluid flowing through the housing ports 60 and into its annular passage 61 can flow through a pair of diametrically opposite side ports 72 in the cylinder sleeve into a peripheral groove 73 in the piston that communicates through a pair of opposed ports 74 with the interior passage 75 of the piston above the plug stem 67. The piston 69 is urged in a downward direction within the housing and along the plug stem 67 by a helical compression spring 76, the lower end of which engages the upper end of the piston, and the upper end of which bears against the flange 77 of a protector tube 78 disposed within the spring, the flange bearing against the downwardly facing shoulder 79 of the flow mandrel section 51. The spring 76 urges the piston 69 downwardly to its fullest extent in which it fully opens the cylinder sleeve ports 72, so that fluid can flow through the full area of such ports and through the piston ports 74 into the interior 75 of the latter. The fluid flows upwardly within the piston and then through a choke orifice 80 provided centrally through an orifice plate 81 mounted in the piston or sleeve valve, the lower end of this plate bearing against an upwardly facing piston shoulder 82, the plate being retained thereagainst by a split snap retaining ring 83 overlying the orifice plate and disposed within an internal groove 84 in the piston. Leakage of fluid around the exterior of the orifice plate 81 is prevented by a side seal ring 85 on the piston sealing against the periphery of the plate.

The fluid pressure acting upwardly upon the orifice plate 81 tends to shift the piston 69 upwardly along the cylinder sleeve 63 against the force of the spring 76 to move the piston partially across the ports 72 of the cylinder sleeve for the purpose of decreasing their effective area and throttling the flow of fluid therethrough and through the piston ports 74 to the interior 75 of the piston. The area of the orifice 80 is chosen to obtain a desired fluid pressure drop therethrough. If this fluid pressure drop tends to vary, the piston is shifted longitudinally in the cylinder sleeve 63 to correspondingly vary the extent of throttling of the ports 72 through the cylinder sleeve 63 and the pressure of the fluid on the upstream side of the orifice plate 81. Thus, if the upstream pressure tends to increase relative to the downstream pressure, or the downstream pressure drop relative to the upstream pressure, so as to increase the pressure differential across the orifice plate 81, the piston 69 is shifted upwardly within the cylinder sleeve against the force of the spring to reduce the flow area through the sleeve ports 72 an'd throttle the flow of fluid therethrough to lower its pressure to the desired valueto produce the proper pressure drop through the orifice plate. Similarly, should the downstream pressure on .the orifice plate increase, or the upstream pres-l sure decrease, the pressure drop across the orifice plate would decrease, the spring 76 shifting the piston 69 downwardly to increase the flow area through the cylinder ports 72 and causing the fluid pressure passing into the piston passage 75 to increase, thereby again restoring the pressure drop across the orifice plate to the desired value. By maintaining this pressure drop constant, the rate of flow of fluid through the orifice 80 is maintained at a constant value.

The fluid discharging from the orifice plate 81 passes upwardly through the protector sleeve or tube 78 and into the central passage 53 of the flow mandrel section, flowing outwardly through the side port 54 and through the boss port 35 and the housing ports 32 to the exterior of the housing structure 20.

Each flow regulator 17 in the tubing string will have a required area of orifice Si) through its orifice plate, depending upon the pressure drop through the orifice plate desired, which is determined by the rate iluid is to ow through the orice plate 81. This governs the rate of low of iluid that will be pumped through the perforations in the casing into the associated formation zone. Assuming that all of the well packers 14, 1S, 16 are set in the well casing F, as disclosed in FIG. 1, and with all of the flow regulators 17 in place, fluid is pumped down through the tubing string H, passing downwardly through the annular space 30 between the housing sleeve 22 and the inner housing section 24 into the lower sub 23 of the uppermost regulator 17. A portion of the fluid will flow through the housing ports 60 of the uppermost regulator and through the cylinder ports 72 and piston ports 74 to the interior 75 of the piston 69, owing through the orice S0 and up through the protective tube '73 and the mandrel passage 53 for outward movement through the mandrel port 54, inner housing port 35, and outer housing ports 32 into the well casing, from where the Huid will pass through the casing perforations 12 into the formation zone C between the uppermost and intermediate well packers 16, 15. The uppermost flow regulator 17 will regulate the iiow of uid passing therethrough 'by the throttliug action of the piston 69 on the cylinder ports 72 to maintain the pressure drop across the orifice plate 81 substantially constant.

Fluid in the tubing string H will also be pumped downwardly from the lower housing sub 23 at the zone C through the tubing string H therebelow for continued downward passage into the flow regulator 17 between the intermediate and lower well packers 15, 14, such fluid passing around the exterior of the regulator housing 58 and upwardly through the internal regulator mechanism for discharge through the housing ports 32 into the well casing and for outward passage through the perforations 11 into the formation zone B between the intermediate and lower packers.

Fluid in the tubing string will also be pumped downwardly through the tubing string H below the intermediate How regulator 17 for passage between the inner and outer housing structures 24, 20 of the lower regulator 17 into the lower housing or body sub 23 of the lower regulator for upward passage through its internal regulator mechanism and for discharge through the ports 32 into the casing below the lower packer 14 for passage through the lowermost set of perfor-ations 10` into the well formation zone A therearound.

The fluid in the single tubing string H is caused to be discharged from each flow regulator 17 into the casing at a predetermined rate of ow. Such rates of ilow may be equal for all llow regulators, if desired, or the proper orifice size can be selected to secure a different rate of flow at two or more of the regulators. The fluid being discharged from each flow regulator 17 into the well casing is independent of the fluid being discharged from the other regulators, but will, nevertheless, result in the injecting of the desired volumetric rate of liquid flow through the perorations of each zone.

In the event that uid tends to ow reversely from a formation zone back through the regulator, such action is prevented Vby the check valve, the ball valve member 37 of which will shift laterally inwardly into engagement with its companion seat 38. Thus, in the event that one of the flow regulator devices is removed or retrieved from the housing structure 24, the formation fluid cannot flow reversely into the tubing string H.

It is to be noted that the injected fluid must pass downwardly around the exterior of each ow regulator within the tubing H and must completely reverse its direction of flow in passing upwardly through the interior of the flow regulator. This change in ow direction causes entrained solids to drop out of the liquid stream into the tubing string H, preventing them from passing up through the regulator mechanism. The entrained solids will be carried downwardly past the lowermost regulator and will drop downwardly therebelow into the tubing string, which has a plug 9i), or is bullnosed at its lower end, for catching the entrained solids. The tubing 91 below the lowerrnost regulator 17 may have an adequate length to insure its capacity to retain all of the entrained solids in the fluid pumped into the tubing string H.

The flow regulators illustrated in FIGS. 3a and 3b are of the retrievable type. If desired, the tubing string H can be run in and placed in sealed relation with the well packers 14, 1S, 16, or the tubing string and well packers may be run in together, the housing structures 2t), 24 being appropriately located in the tubing string. The lowermost flow regulator is then lowered through the tubing string on a suitable running-in tool (not shown) which retains its latches 43 in their retracted position until the lowermost regulator housing 24 is reached, at which time the latches are released and will be expanded by their springs 47 into the circumferential lock groove 4d, which locates the mandrel seals 56, .77 on opposite sides of the housing port 35, and which also prevents the fluid pumped subsequently down through the tubing string from shifting the mandrel and regulator device from the housing 24 therearound.

The ow regulators in upward sequence are then run successively into the tubing string H and placed in their companion housing structures 20, 24, with the lock dogs 43 being permitted to be expanded out into their respective lock grooves 46, until all of the ow regulators are in place.

Fluid in the desired volume and under the required pressure is then pumped down through the tubing string H and through the flow regulators 17 through the several perforations 10, 11, 12 into the different zones A, B, C, the flow regulators maintaining the rate of flow at their respective desired constant values in the manner described above. The well packers 14, 15, 16 may have previously been set against the well casing F, or they may be of the hydraulically expandable type in which the uid pressure in the tubing string will effect expansion of the packers against the wall of the well casing.

If at any time the regulators are to be removed from the tubing string, a suitable retrieving tool (not shown) is lowered on a wire line through the tubing string H to retract the lock dogs 43 and become coupled to the upper head portion 5G of the lock mandrel section 41 of each regulator, permittiny the entire regulator mechanism to be removed from t-he inner housing and withdrawn through the tubing string to the top of the well bore. The uppermost, intermediate, and lowermost regulators are thus successively retrieved.

It is accordingly, apparent that a multiple zone injection apparatus has been provided which will insure the injection of the desired quantity of fluid into each of the formation zones. As many packers and regulators can be used as necessary in connection with the single string of tubing, assurance being had that the desired quantity of nid will be injected from each regulator between each pair of well packers, and also from the regulator below the lowermost packer. Such injection can take place with the use of one string of tubing, eliminating the need for multiple or parallel strings of tubing and their associated relatively complex well packers.

1f desired, fluid may be injected into a zone D above the uppermost well packer 16 through use of a surface ow regulator 18. -As disclosed in FIG. 1, perforations 13 are provided in the well casing opposite this uppermost zone above the uppermost well packer 16, and the tubing str-ing M is connected to tlhe well Ihead I for discharging iluid into the annulus 19 between the other tubing string H and the well casing F. The surface flow regula-tor 18 is of the same type as the ow regulator illustrated in FIGS. 3a and 3b. As shown, it includes a main housing or body 20w threadedly secured to sections 92, 93 of the tubing M to hold them in spaced relation. Fluid will flow from one tubing section 92 through the inlet end 94 of the housing and into an annular space 61a between the cylinder sleeve 63 and the enlarged bore 62a of the housing, flowing inwardly through the cylinder ports 72 and through the ports 74 of the piston 69 which is s-lidable in the cylinder, and also in the annular space 68 between the plug stem 67 and the cylinder, the plug being piloted within the cylinder with its flange 65 engaging the end of the latter and being held in place by a cross pin 9S at its outer end extending in opposed bores 96 in the outer end portion of the housing.

The fluid discharging through the piston ports 7S to its interior will flow through the orifice 80 of the orifice plate 81 and through the protector tube 78 and the central outlet 32a of the housing into the tubing section 93 on its downstream side, flowing therethrough into the tubingcasing annulus 19 for outward flow through the casing perforations 13 into the uppermost zone D. Tlhe spring 76 tends to shift the piston 69 to a position fully opening the cylinder ports 72; whereas, the pressure differential across the orifice plate 81 tends to shift the piston in a downstream direction to throttle the flow of fluid through the ports 72, in the same manner as the regulator disclosed in FIGS. 3a and 3b, for the purpose of maintaining the pressure drop across the orifice plate substantially constant, and consequently maintaining the rate of flow of fluid into the tubing-casing annulus 19 and through the perforations 13 into the uppermost zone D substantially constant.

I claim:

1. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zones from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the well bore in sealed relation to said tubing string to isolate the formation zones from one another; a separate flow regulator in said tubing string at each zone to conduct fluid from said tubing string into each zone; each flow regulator including flow restricting means to reduce the pressure of the fluid received from said tubing string, whereby reduced pressure fluid is discharged individually from each flow regulator for passage into its associated formation zone; each of said flow regulators further including means for maintaining the fluid pressure dlr-op across its flow restricting means substantially constant.

2. In apparatus for injecting fluid into a plurality of formation zone regions from the top of a well bore: a tubing string in the well bore; packing means adapted to be set inthe well bore and in sealed relation to said tubing string to isolate the formation zone regions from one another; a separate Aflow regulator in said tubing string at each formation zone region to conduct fluid from said tubing string into each formation zone region; each flow regulator including flow restricting means to reduce the pressure of the fluid received from said tubing string, whereby reduced pressure fluid is discharged individually from each flow regulator for passage into its associated formation zone region; each flow regulator having an outlet through which fluid is discharged for passage into its associated formation zone region, and an inlet substantially below said outlet for receiving fluid from the interior of said tubing; each of said flow regulators further including means for maintaining the fluid pressure drop across its flow restricting means substantially constant.

3. In apparatus for injecting fluid into a plurality of formation zone regions from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the well bore and in sealed relation to said tubing string to isolate the formation zone regions from one another; a separate flow regulator in said tubing str-ing at each formation zone region to conduct fluid from said tubing string into each formation zone region; each flow regulator including an orifice to reduce the pressure of the fluid flowing from the tubing string to its associated formation zone region, whereby reduced pressure fluid is discharge individually from each flow regulator for passage into its associated formation zone region, each flow regulator having an outlet through which fluid is discharged for passage into its associated formation zone region, and an inlet substantially below said outlet for receiving fluid from the interior of said tubing; each of said flow regulator further including means for maintaining the fluid pressure ldrop across its orifice substantially constant.

4. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zones from the top of a Well bore: a tubing string in the well bore; packing means adapted to be set `in the well bore in sealed relation to said tubing string to isolate the formation zones from one another; a separate flow regulator in said tubing string at each zone to conduct fluid from said tubing string into each zone; each flow regulator including au orifice to reduce the pressure of the fluid flowing from the tubing string to its associated formation zone, whereby reduced pressure fluid is discharged individually from each flow -regulator for passage into its associated formation zone; each of said flow regulators further including means for maintaining t-he fluid pressure drop across its orifice substantially constant.

5. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zones from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the well bore in sealed relation to said tubing string to isolate the formation zones from one another; a separate flow regulator in said tubing string at each zone to conduct fluid from said tubing string into each zone; each flow regulator including an orifice to reduce the pressure of the fluid flowing from the tubing string to its associated formation zone, whereby reduced pressure fluid is discharged individually from each flow regulator for passage into its associated formation zone; each of s-aid flow regulators further including means upstream of its orifice for maintaining the fluid pressure drop across its orifice substantially constant.

6i. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zone regions from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the well bore in sealed relation to said tubing string to isolate the formation zone regions from one another; a separate `flow regulator in said tubing string at each form-ation zone region to conduct fluid from said tubing string into each formation zone region; each flow regulator including an orifice to reduce the pressure of the fluid flowing from the tubing string to its associated formation zone region, whereby reduced pressure fluid is discharged individually from each flow regulator for passage into its associated formation zone region; each flow regulator having an outlet above its orifice through which fluid is discharged for passage into its associated formation zone region, each flow regulator further including means upstream of and below its orifice for maintaining the fluid pressure drop across its orifice substantially constant.

7. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zones from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the well bore in sealed relation to said tubing string to isolate the formation zones from one another; a separate flow regulator in said tubing string at each zone to conduct fluid from said tubing string into each zone; each flow regulator including a valve body having a port, a sleeve valve movable across said body port to control the effective area thereof through which fluid from said tubing string can flow, orifice means secured to said sleeve valve to shift said sleeve valve relative to said body port and to reduce the pressure of the fluid flowing from said body port to its associated formation zone, whereby reduced pressure fluid at a substantially constant flow rate is discharged individually from each flow regulator for passage into its associated formation zone.

8. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zone regions from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the well bore and being in sealed rela-tion to said tubing string to isolate the formation zone regions from one another; a separate flow regulator in said tubing string at each formation zone region to conduct fluid from said tubing string into each formation zone region; each flow regulator including a valve body having a port, a sleeve valve movable across said body port to control the effective area thereof through which fluid from said tubing string can flow, orifice means secured to said sleeve valve above said port to shift said sleeve valve relative to said body port and to reduce the pressure of the fluid received from said body port, each flow regulator having an outlet above its orifice through which fluid is discharged for passage into its associated formation zone region, whereby reduced pressure fluid at a substantially constant flow rate is discharged individually from each flow regulator for passage into its associated formation zone region.

9. ln apparatus for injecting fluid into a plurality of longitudinally spaced formation zones from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the well bore and `being in sealed relation to said tubing string to isolate the formation zones from one another; said tubing string having a separate outlet for each formation zone; a separate flow regulator for each zone movable through the tubing string from the top of the well bore to a location therein at an associated zone and having an outlet communicating with said tubing string outlet at its associated zone; each flow regulator including flow restricting means to reduce the pressure of the fluid received from said tubing string, whereby reduced pressure fluid is discharged individually from each flow regulator and through its associated tubing string outlet for passage into its associated formation zone; each of said flow regulators further including means for maintaining the fluid pressure drop across its flow restricting means substantially constant.

1li. ln apparatus for injecting fluid into a plurality of longitudinally spaced formation zones from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the Well bore and being in sealed relation to said tubing string to isolate the formation zones from one another; said tubing string having a separate outlet for each formation zone; a separate flow regulator for each zone movable through the tubing string from the top of the well bore to a location therein at an associated Zone and having an outlet communicating with said tubing string outlet at its associated zone; each flow regulator including flow restricting means to reduce the pressure of the fluid received from said tubing string, whereby reduced pressure fluid is discharged individually from each flow regulator and through its associated tubing string outlet for passage into its associated formation zone; and valve means at each tubing string outlet for preventing reverse flow of fluid through said tubing string outlet.

l1. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zone regions from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the well bore and being in sealed relation to said tubing string to isolate the formaation zone regions from one another; said tubing string having a separate outlet for each formation zone region; a separate flow regulator for each formation zone region movable through the tubing string from the top of the well bore to a location therein at an associated formation zone region and having an outlet communicating with said tubing string outlet at its associated formation zone region;

each flow regulator including flow restricting means to reduce the pressure of the fluid received from said tubing string, whereby reduced pressure fluid is discharged individually from each flow regulator and through its associated tubing string youtlet for passage into its associated formation zone region; each flow regulator having an inlet substantially below the outlet of said flow regulator for receiving fluid from the interior of said tubing; each of said flow regulators further including means for maintaining the fluid pressure drop across its flow restricting means substantially constant.

12. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zones from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the well bore and being in sealed relation to .said tubing string to isolate the formation zones from one another; said tubing string having a separate outlet for each formation zone; a separate flow regulator for each zone movable through the tubing string from the top of the well bore to a location therein at an associated zone and having an outlet communicating with said tubing string outlet at its associated zone; each flow regulator including a valve body having a port, a sleeve valve movable across said body port to control the effective area thereof through which fluid from said tubing string can flow, orifice means secured to said sleeve valve to shift said sleeve valve relative to said body port and to reduce the pressure of the fluid received from said body port and flowing to its associated tubing string outlet and its associated formati-on zone, whereby reduced pressure fluid at a substantially constant flow rate is discharged individually from each flow regulator for passage into its associated formation zone.

13. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zones from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the Well bore and being in sealed relation to said tubing string to isolate the formation zones from one another; said tubing string having a separate outlet for each formation zone; a separate flow regulator for each zone movable through the tubing string from the top of the well bore to a location therein at an associated zone and having an outlet communicating with said tubing string outlet at its associated zone; each flow regulator including a valve body having a port; a sleeve valve movable across said body port to control the effective area thereof through which fluid from said tubing string can flow, orifice means secured to said sleeve valve to shift said sleeve valve relative to said body port and to reduce the pressure of the fluid received fr-om said body port and flowing to its associated tubing string outlet and its associated formation zone, whereby reduced pressure fluid at a substantially constant flow rate is discharged individually from each flow regulator for passage into its associated formation zone; and valve means at each tubing string outlet for preventing reverse flow of fluid through said tubing string outlet.

14. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zone regions from the top of a Well bore: a tubing string in the well bore; packing means adapted to be set in the well bore and being in sealed relation to said tubing string to isolate the formation zone regions from one another; said tubing string having a separate outlet for each formation zone region; a separate flow regulator for each formation zone region movable through the tubing string from the top of the well bore to a location therein at an associated formation zone region and having an outlet communicating with said tubing string outlet at its associated formation zone region; each flow regulator including a valve body having a port below said flow regulator outlet, a sleeve valve movable across said body port to control the effective area thereof through which fluid from said tubing string can flow, orifice means secured to said sleeve valve between said flow regulator port and said flow regulator outlet to shift said sleeve valve relative to said body port and to reduce the pressure of the fluid flowing from said body port to its associated formation Zone region, whereby reduced pressure fluid at a substantially constant flow rate is discharged from each flow regulator outlet for passage through its associated tubing string outlet into its associated formation Zone region.

15. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zone regions from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the well bore and being in sealed relation to said tubing string to isolate the formation zone regions from one another; said tubing string having a separate outlet for each formation zone region; a separate flow regulator for each formation zone region movable through the tubing string from the top of the well bore to a location therein at an associated formation zone region and having an outlet communicating with said tubing string outlet at its associated formation Zone region; each flow regulator including a valve body having a port below said flow regulator outlet, a sleeve valve movable across said body port to control the effective area thereof through which fluid from said tubing string can flow, orifice means secured to said sleeve valve between said flow regulator port and said flow regulator outlet to shift said sleeve valve relative to said body port and to reduce the pressure of the fluid flowing from said body port to its associated formation zone region, whereby reduced pressure fluid at a substantially constant flow rate is discharged from each flow regulator outlet for passage through its associated tubing string outlet into its associated formation zone region; and valve means in each tubing string outlet for preventing reverse flow of fluid through said tubing string outlet.

16. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zones from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the well bore and being in sealed relation to said tubing string to isolate the formation zones from one another; said tubing string having a separate outlet for each formation zone; a separate flow regulator for each zone movable through the tubing string from the top of the well bore to a location therein at an associated zone and having an outlet communicating with said tubing string outlet at its associated zone; each flow regulator including flow restricting means to reduce the pressure of the fluid received from said tubing string, whereby reduced pressure fluid is discharged individually from each flow regulator and through its associated tubing string outlet for passage into its associated formation zone; each flow regulator further including means for maintaining the fluid pressure drop across its flow rcstricting means substantially constant; and valve means in each regulator for preventing reverse flow of fluid from said tubing string outlet and through said regulator.

17. In apparatus for injecting fluid into a plurality of longitudinally spaced formation zones from the top of a well bore: a tubing string in the well bore; packing means adapted to be set in the well bore and being in sealed relation to said tubing string to isolate the formation zones from one another; said tubing string having a separate outlet for each formation zone; a separate flow regulator for each zone movable through the tubing string from the top of the well bore to a location therein at an associated zone and having an outlet communicating with said tubing string outlet at its associated zone; each flow regulator including a valve body having a port, a sleeve valve movable across said body port to control the effective area thereof through which fluid from said tubing string can flow, orifice means secured to said sleeve valve to shift said sleeve valve relative to said body port and to reduce the pressure of the fluid received from said body port and flowing to its associated tubing string outlet and its associated formation zone, whereby reduced pressure fluid at a substantially constant flow rate is discharged individually from each flow regulator for passage into its associated formation zone; and valve means in each regulator for preventing reverse flow of fluid from said tubing string outlet and through said regulator.

References Cited by the Examiner UNITED STATES PATENTS 2,537,066 l/l95l Lewis 166-115 2,646,078 7/1953 Adams 137-501 2,865,397 12/1958 Chenault 137-501 X 2,869,645 1/1959 Chamberlain et al. 166-224 X 2,869,646 l/l959 Chamberlain et al. 166-133 2,881,794 4/1959 Baldwin et al 137-501 2,973,039 2/1961 Payne 166-10 X CHARLES E. OCONNELL, Primary Examiner.

D. H. BROWN, Assistant Examiner. 

1. IN APPARATUS FOR INJECTING FLUID INTO A PLURALITY OF LONGITUDINALLY SPACED FORMATION ZONES FROM THE TOP OF A WELL BORE: A TUBING STRING IN THE WELL BORE; PACKING MEANS ADAPTED TO BE SET IN THE WELL BORE IN SEALED RELATION TO SAID TUBING STRING TO ISOLATE THE FORMATION ZONES FROM ONE ANOTHER; A SEPARATE FLOW REGULATOR IN SAID TUBING STRING AT EACH ZONE TO CONDUCT FLUID FROM SAID TUBING STRING INTO EACH ZONE; EACH FLOW REGULATOR INCLUDING FLOW RESTRICTING MEANS TO REDUCE THE PRESSURE OF THE FLUID RECEIVED FROM SAID TUBING STRING, WHEREBY REDUCED PRESSURE FLUID IS DISCHARGED INDIVIDUALLY FROM EACH FLOW REGULATOR FOR PASSAGE INTO ITS ASSOCIATED FORMATION ZONE; EACH OF SAID FLOW REGULATORS FURTHER INCLUDING MEANS FOR MAINTAINING THE FLUID PRESSURE DROP ACROSS ITS FLOW RESTRICTING MEANS SUBSTANTIALLY CONSTANT. 